Abnormal orientation bias of LGN neurons in strabismic cats

The reduced visual sensitivity of strabismic amblyopes is often accentuated when they view vertical as opposed to horizontal gratings ("vertical effect"). Earlier attempts to show neurophysiological correlates of the vertical effect in strabismic cats have yielded controversial findings. We now report the results of experiments in the lateral geniculate nucleus (LGN) that clearly demonstrate the reduced sensitivity of X-cells in strabismic cats to vertical gratings as compared to horizontal ones. We conclude that the neural basis for the vertical effect is present at least at the level of the LGN.

Ten-year-replicated circadian profiles for 36 physiological, serological and urinary variables in healthy men

At 3-hr intervals over a 24-hr span, 36 systemic, serologic and urinary variables were examined in 7 men in their mid 20's in the Spring of 1969, and again in the same 7 men in the Spring of 1979 under a similar chronobiologic protocol, using the same chemical and numerical analytical procedures. The variables examined for rhythms by cosinor were: vital signs--blood pressure (systolic, diastolic, pulse pressure and mean arterial pressure), heart rate, intraocular pressure (left and right), oral temperature; serum components--albumin, albumin/globulin ratio, total bilirubin, calcium, carbon dioxide, chlorides, bilirubin, cholesterol, globulin, glucose, potassium, sodium, sodium/potassium ratio, transaminase, triglycerides, total protein, urea nitrogen; and urine components--calcium, calcium/magnesium ratio, creatinine, magnesium, pH, potassium, sodium, sodium/potassium ratio, urea clearance, urea nitrogen, volume and zinc. Although all subjects appeared clinically healthy in 1969 and in 1979, certain inter-study differences were observed in a number of rhythm parameters of different variables. Statistically significant increases in mesor for the group as a whole were observed for serum Ca, cholesterol, Cl, CO2, K, Na, and while statistically significant mesor decreases for a group as a whole were noted in serum glucose and transaminase. Statistically significant increases in amplitude for the group as a whole were observed in serum chloride and urinary Na/K ratio, while statistically significant decreases were observed in amplitude for blood pressure, heart rate, serum albumin, A/G ratio, globulin, glucose, protein, sodium and transaminase.(ABSTRACT TRUNCATED AT 250 WORDS)

Demonstration of focal hyperemia in acute cerebral infarction with iodine-123 iodoamphetamine

Focal hyperemia is known to occur in regions of acute cerebral infarction. Presented here are two cases in which SPECT images with 125I-labeled iodoamphetamine demonstrated focal areas of increased tracer concentration associated with cerebral infarction. These results may have important implications regarding the physiology of iodoamphetamine in cerebral infarction and, in particular, whether the distribution of this tracer is related to regional blood flow in this setting. In addition, interpretation of iodoamphetamine images in cerebral infarction should include consideration of this finding.

Blood pressure and cognitive performance. The Framingham Study

In 1976-1978, a battery of eight neuropsychologic tests were administered to 2,123 participants in the Framingham Study who were aged 55-89 years. Performance on each test was examined in relation to concurrently measured systolic and diastolic blood pressure while controlling for age, sex, education, antihypertensive medication, alcohol consumption, and smoking. Those with a diagnosis of stroke were excluded from the analysis. In the remaining sample of 2,032, neither blood pressure nor antihypertensive treatment was significantly associated with cognitive performance. Even after excluding persons on antihypertensive medication, blood pressure was still unrelated to cognitive performance. In contrast to other studies, the authors found no consistent relation between blood pressure and cognitive performance.

Contrast affects the transmission of visual information through the mammalian lateral geniculate nucleus

1. We recorded with one electrode action potentials of single principal cells in the lateral geniculate nucleus (l.g.n.) of cats and monkeys, together with their retinal inputs, recorded as synaptic potentials (S potentials; Bishop, Burke & Davis, 1958; Cleland, Dubin & Levick, 1971; Kaplan & Shapley, 1984). 2. We studied the effect of stimulus contrast on the transmission of visual information from the retina to the l.g.n., compared the spontaneous discharge of l.g.n. cells with that of their retinal inputs, and studied the driven (modulated) and maintained (unmodulated) discharge of l.g.n. neurones and their retinal drives. 3. The spontaneous discharge of l.g.n. cells was considerably lower than that of their retinal drives. 4. The maintained (unmodulated) discharge of l.g.n. cells during stimulation was lower than that of their retinal drives, and was largely unaffected by the stimulus contrast. 5. The responses of both the retinal input and l.g.n. cells increased with contrast, but at different rates: a given increment of contrast caused a larger increment of response in the retinal input than in the l.g.n. target cells. 6. The transmission ratio (l.g.n. response/retinal response) for most cells depended upon the stimulus contrast. This dependence indicates the presence of a non-linear contrast gain control. 7. The amount by which the l.g.n. attenuated the retinal input depended upon the temporal frequency, and, to a lesser extent, upon the spatial frequency of the stimulus. 8. The effect of contrast on signal transmission between the retina and l.g.n. was essentially the same in the macaque monkey as in the cat. 9. The attenuation of the retinal input by the l.g.n. contrast gain control could serve to prevent saturation and extend the dynamic range of cortical units, which probably receive input from several l.g.n. units.

Malignant fibrous histiocytoma metastatic to the thyroid gland

Despite frequent cancer metastases to the thyroid gland demonstrated at autopsy, finding of thyroid metastasis in clinical practice is rare. Malignancies most commonly metastasizing to the thyroid are malignant melanoma and carcinoma of the breast, kidney, and lung. Very little is known about thyroid metastases caused by sarcomas. Of these, malignant fibrous histiocytoma (MFH) is one of the most common in adults, with a high rate of metastases. A case of clinically significant thyroid metastasis from primary MFH involving the thigh visualized on I-123 thyroid imaging is reported.

Linear mechanism of orientation tuning in the retina and lateral geniculate nucleus of the cat

1. The orientation tuning of lateral geniculate nucleus (LGN) neurons and retinal ganglion cells (recorded as S potentials in the LGN) was investigated with drifting grating stimuli. 2. Results were compared with a quantitative model, in which receptive fields were constructed from linear, elliptical Gaussian center and surround subunits, and responses could be predicted to gratings of any spatial frequency at any orientation. 3. The orientation tuning of X and Y retinal ganglion cells and LGN neurons was shown to result from the linear mechanism of receptive-field elongation, as data from these cells could be well fit with this model. 4. The responses of LGN neurons and their input retinal ganglion cells were compared. The orientation tuning of LGN neurons was found to be a reflection of the tuning of their retinal inputs, showing that neither intrageniculate neural interactions nor the corticogeniculate projection play any role in LGN orientation selectivity.

Incidence of familial dysautonomia in Israel 1977-1981

The incidence of all diagnosed cases of familial dysautonomia in Israel among Ashkenazi Jews from 1977-1981 was 27/100,000 or 1/3703. This incidence is higher than that previously reported in Israel in 1967 or 8.3/100,000 (1/12,048) (Moses et al. 1967). It is also higher than that of North American Ashkenazi Jews in 1970, when the rate was 5-10/100,000 (1/10,000-20,000) (Brunt & McKusick 1970). This higher incidence could be explained by current awareness of the diagnosis, or by the emergence of more cases.

Neuropsychological test performance in Framingham: a descriptive study

In 1976–1978, a battery of eight neuropsychologic tests was administered to 2,123 participants in the Framingham Study aged 55 to 89 yr. The battery was designed to sample multiple areas of cognitive function including language skills, memory, learning, reproduction of designs, attention, and abstract thinking. Performance is described for several groups in this population: a large community-dwelling sample, those with hearing impairments, and those with documented strokes. Performance is described by age, sex, and education strata for the community sample. This normative information should be useful for interpreting individual test performance on neuropsychological tests.

Visualization of metastatic liver disease on technetium-99m bone scintigraphy

To determine the frequency with which liver metastases are visualized on bone scintigraphy, 425 pairs of liver and bone scans, performed within one month of each other, were reviewed. Sixty-three of the 425 liver scans showed metastases. Of these 63, five cases of carcinoma of the colon and six cases of carcinoma of the lung also visualized by Tc-99m MDP scintigraphy. This represented 46% of colon metastases and 15% of lung metastases detected on liver scan. Liver metastases from other primary tumors were not detected on bone scan, but the numbers for these tumors were small. The liver metastases which were detected on bone scan were significantly larger than those which were not. The literature was reviewed and the primary and secondary tumors of liver with uptake of Tc-99m phosphate compounds listed.

Clinical and histologic features of nevi with emphasis on treatment approaches

A nevus is a cutaneous lesion characterized histologically by clustering and disorganization of a variety of cell types in the skin including the epidermis, appendages, melanocytes, and their precursor cells. Commonly, a nevus is congenital but it may be acquired. Owing to the prevalence and variations of melanocytic nevi and their association with malignancy, this article discusses the development, classification, histology, and clinical characteristics of nevi with an emphasis on the relationship to malignancy. Recommendations are provided for treatment of these benign lesions.

Circadian rhythms in Limulus photoreceptors. I. Intracellular studies

The sensitivity of the lateral eye of the horseshoe crab, Limulus polyphemus, is modulated by efferent optic nerve impulses transmitted from a circadian clock located in the brain (Barlow, R. B., Jr., S. J. Bolanowski, and M. L. Brachman. 1977. Science. 197:86-89). At night, the efferent impulses invade the retinular, eccentric, and pigment cells of every ommatidium, inducing multiple anatomical and physiological changes that combine to increase retinal sensitivity as much as 100,000 times. We developed techniques for recording transmembrane potentials from a single cell in situ for several days to determine what circadian changes in retinal sensitivity originate in the primary phototransducing cell, the retinular cell. We found that the direct efferent input to the photoreceptor cell decreases its noise and increases its response. Noise is decreased by reducing the rate of spontaneous bumps by up to 100%. The response is increased by elevating photon catch (photons absorbed per flash) as much as 30 times, and increasing gain (response per absorbed photon) as much as 40%. The cellular mechanism for reducing the rate of spontaneous quantum bumps is not known. The mechanism for increasing gain appears to be the modulation of ionic conductances in the photoreceptor cell membrane. The mechanism for increasing photon catch is multiple changes in the anatomy of retinal cells. We combine these cellular events in a proposed scheme for the circadian rhythm in the intensity coding of single photoreceptors.

Time-based multiple organ functional images

Computer generation of functional images has gained recognition as a valuable method of analyzing physiologic data. However, most mathematical models used to produce these images are frequency-based, which requires that the entire function be examined. Because frequency-based characteristics are only indirectly related to physiologic characteristics, this technique has inherent deficiencies that may be minimized through various manipulations. Our technique is to base such images on time-related features, rather than frequency-based. This technique deals directly with regional count rate behavior, which in turn reflects function. Benefits from such an approach include the ability to generate images from isolated portions of an event and the removal of sinusoidal models that may or may not accurately represent function. Our experience with such an approach to the generation of functional images of the heart, lungs, and liver has been highly successful.

A randomized study of methotrexate, bleomycin, hydroxyurea with versus without cisplatin in patients with previously untreated and recurrent squamous cell carcinoma of the head and neck

The value of a combination of methotrexate, bleomycin and hydroxyurea with vs. without cisplatin was randomly examined in 62 evaluable patients with previously untreated (44 patients) and recurrent (18 patients) squamous cell carcinoma of the head and neck. Methotrexate (30 mg/m2) and bleomycin (15 mg) were given intravenously weekly, hydroxyurea (1000 mg/m2) per os 3 times per week for 4 weeks. Cisplatin (60 mg/m2) was added on Day 1 every month. A higher overall response rate was observed with the cisplatin-containing regimen (66%, included 17% complete) as compared with 27% (3% complete) with the 3-drug combination (P value 0.0025). The cisplatin-containing regimen was more active in both previously untreated patient group and in the group recurrent patients. Toxicity was more pronounced in the cisplatin regimen and necessitated frequently reduced drug dosages. No survival difference was observed between the treatment groups. Median survival in previously untreated patients was 16.2 months and 7.2 months in patients who failed conventional local treatment. It is concluded that a cisplatin-containing regimen is more effective in advanced head and neck carcinoma than the same combination without cisplatin.

Fourth ventricle effects of nicotine, 2-methylpiperidine and cytisine in dogs

Four distinguishable nicotinic binding sites have been identified as well as four nicotinic ligands with different specificities: (+/-)-2-methylpiperidine which binds to a very high affinity site (Site 1) and produces up-regulation of the high affinity site (Site 2); (-)-nicotine which binds to Site 1 and Site 2 as well as to a low affinity site (Site 4); (+)-nicotine which binds to Site 1, Site 4 and Site 3 which is also a high affinity site; and (-)-cytisine which binds to Sites 1 and 2. These drugs were injected into the 4th ventricle of 5 dogs in graded concentrations (12.5 to 400 micrograms) and their effects on the EEG, skin twitch reflex latency, heart rate, rectal temperature, pupillary diameter, blood pressure and the amplitude of the flexor reflex were measured. Drugs which act predominantly on Site 1 [(+/-)-2-methylpiperidine and (+)-nicotine] produced EEG synchronization and hyperalgesia while drugs which interact with Sites 2 and 4 produce EEG desynchronization, analgesia and tachycardia. These data indicate that nicotinic ligands which have different binding specificities have different actions in medullary function and support the hypothesis that the different binding sites have different pharmacologic significance.

Hyperbaric oxygenation and erythrocyte antioxidant enzymes in multiple sclerosis patients

Erythrocyte glutathione peroxidase, catalase, and superoxide dismutase activities were measured in 18 patients with clinically definite MS, and results compared with those from neurological controls. These studies indicated that glutathione peroxidase activity in erythrocytes of MS patients was not different from that of the neurological controls. However, superoxide dismutase was lower in the MS patients compared to neurological controls. The effect of hyperbaric oxygenation on these erythrocyte enzymes in MS patient's was also investigated. Exposure of MS patients to 2 ata with either 10% O2 or 100% O2 had no effect on glutathione peroxidase activity. Comparison of each individual MS patient's pre- and post-treatment superoxide dismutase values indicated a significant increase after 100% O2. Similar examination of each individual's catalase activity indicated an increase after exposure to both 10% O2 and 100% O2 at 2 ata. These data suggest that erythrocyte enzyme response to oxygen stress does not involve changes in activity of all the antioxidant enzymes. Instead, only specific enzymes appear to be affected by HBO.

Effect of acute postinfusion lipemia and free fatty acids on myocardial contractility: assessment with radionuclide ventriculography

Equilibrium gated radionuclide ventriculography was used to evaluate the effect of intravenous fat-emulsion overload and excess of free fatty acids (FFA) on left ventricular ejection fraction (LVEF) in 20 patients with and without coronary artery disease (CAD). Fifteen of these patients had normal (greater than 50%) baseline LVEF and 5 had low (less than 50%) baseline LVEF. From 100 to 150 ml of 20% artificial fat emulsion (Liposyn) was infused over 20-25 min. At the end of the infusion, triglyceridemia reached 820 +/- 220 mg% and left ventricular ejection fraction decreased from baseline 62 +/- 19% (mean +/- SD) to 58 +/- 16% (P less than 0.05, paired t-test). After completion of Liposyn infusion, 5,000 U of heparin was administered intravenously and monitoring of LVEF was continued. One and one-half hours following heparin administration, plasma FFA levels reached 3.7 + 2.0 mmol/l and LVEF rose to 69 +/- 19% (P less than 0.001, paired t-test). Our data indicate that acute intravenous fat overload can suppress and high pathophysiologic levels of FFA can increase LVEF. This effect is more uniform and statistically more reliable in patients with normal LVEF. The study failed to demonstrate any significant difference in the effect of this pharmacologic intervention between patients with and without CAD.

Depression influences intellectual impairment in stroke patients

Patients with ischaemic lesions of the left cerebral hemisphere were examined for depression and intellectual impairment: in non-depressed patients, the severity of impairment was related to both lesion volume and location, as assessed by CT scan analysis. Cognitive impairment in patients with major depression was greater than predicted by lesion volume alone, and when patients were matched for severity of impairment, depressed patients had smaller lesion volumes than the non-depressed. After six months, non-depressed patients had significantly less cognitive impairment than depressed patients who showed no improvement. Both depression and lesion volume were significantly and independently related to cognitive impairment. These findings suggest that post-stroke depression can produce a true dementia in its own right, and that treatment of post-stroke depression might benefit cognitive function.

The primate retina contains two types of ganglion cells, with high and low contrast sensitivity

Previously, we discovered that the broadband cells in the two magnocellular (large cell) layers of the monkey lateral geniculate nucleus (LGN) are much more sensitive to luminance contrast than are the color-sensitive cells in the four parvocellular (small cell) layers. We now report that this large difference in contrast sensitivity is due not to LGN circuitry but to differences in sensitivity of the retinal ganglion cells that provide excitatory synaptic input to the LGN neurons. This means that the parallel analysis of color and luminance in the visual scene begins in the retina, probably at a retinal site distal to the ganglion cells.